VFD Spindle Testing

CNC Machines Shapeoko Pro
1

Hey,
Does anyone here know how to test the carbide spindle kit?

I have my bits programmed to run at 18000 rpm but I’ve noticed that the read out on the VFD is only at 16250…
I have a feeling that my VFD isn’t operating correctly, though I can definitely be wrong.
Thank you in advance.

Also, side note, does anyone know the code that pulls up the jog menu on Carbide Motion when you do NOT have a job loaded?

Edit: I figured out how to test my VFD, still unsure of why it is not spinning up to my programmed speed

2

I noticed the same thing with my C3d spindle kit. I asked here but didn’t get much response so I started a support ticket. C3d told me it was normal to have about a 10% difference in rpm :person_shrugging:. I just adjust accordingly in CC to account for this. No big deal for me.

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3

thank you for your reply. i reached out to support and they stated the same, the 16250 im seeing is 18000 - 10%

a little annoying, but it is what it is i suppose!

4

I would suggest checking spindle rpms first. I have an app for my iPhone that makes this easy.

There are settings in the vfd to tweak the rpm output and the displayed rpm but I’m pretty sure carbide locks you out of them.

5

When you say you account for the difference, do you just add 10% to the RPM you want? like I want 18,000, so do I program 19,800?

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Im unsure if its the same 10% everytime or of it fluctuates ,would also like to know.

7

Yea, I just add 10% like you described. I actually created custom profiles for the bits I use commonly. For example, I made custom profile for my 1/4” endmill and set the tool rpm to 20000. That gets me about 18200 rpm or so on my VFD.

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8

Thanks for clarifying!

9

for myself i have noticed it is not 10% everytime, its fluctuates between 5-10 for me. so there are times where i find when i set my speed to 21000 it spins at 19270 ive seen it go as high as 19800.

10

I guess it’s one of those things where your mileage may very.

11

Im curious if this is an em60 vfd specific variance or if its common on all 2.2kw 220 vfds.

12

It is not a issue of the VFD itself but of the PWM signal it receives from the controller. The PWM signal variances are not linear and can fluctuate by 5-50 RPM based off of temperature. You can use a custom post processor to interpolate the correct speed based off of a calibration table to get within 0-10RPM of intended setpoint.

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